Use C++ class from C#

Question

Alright so I have this C++ image capturing class. I was wondering if I could get some help..I know basic C++ (I have done one intro to c and one intro to c++ class) and I have NO idea how to do this:

I need to use this class (ie create a new c++ project in my solution) and use c# to reference it and use it to save a screenshot of the screen.

When I try to add a new project I dont know which one to choose (win32, mfc, atl, clr, abc, xyz, and so on) .

The image capturing class is here: http://pastebin.com/m72414ab

I don't know if I need to create .h files or just a .cpp file would do.. like honestly I have no clue where to start lol. I am looking for a solution, but i want to learn in the process so I dont have to ask next time (not to mention that I like c++ so I am gonna continue coding with it)

Answer 1

You cannot easily use C++ classes from C# without knowing some somewhat specialized information about C++/CLI - either rewrite your C++ class in C and use P/Invoke, or find a fully C# solution.

But I'd like to use this c++ class for speed and memory.

I question this, unless you are capturing images thousands of times a second, there's no way choosing C++ would be of any benefit, and it makes your program much more complicated. Stick with C# until you know you need the slight performance boost.

Answer 2

.NET version 2.0 and above include a CopyFromScreen method on the Graphics object. You can create an image, obtain a drawing surface (Graphics) for that, and then copy from the screen into the image.

A quick bit of Googling produced a simple tutorial which demonstrates this using Visual Basic .NET, although it's trivial to port to C#.

This solution results in the same GDI+ calls that your C++ version uses, with the benefit of not having to link in external C++ code (which, as mentioned above, is not straightforward).

Answer 3

It is definitely possible to use C++ constructs from C#, but it does require some dirty tricks. If I remember correctly, last time I tried to do this I used a Managed C++ layer between C++ and C#, and I think this is the most common way to do it. This method worked well, but indeed was unnecessarily complicated.